Erectile Dysfunction (ED)Phase 2NCT07601646
A Single-Arm, Dose Escalation of an Intraurethral Alprostadil Paste for Erectile Dysfunction
A Phase 2 study testing ST-04 in people with Erectile Dysfunction (ED) and Erectile Dysfunctions, run by Ryan Flannigan, MD at 1 site in Canada.
Trial summary
This is a single arm dose escalation trial of a mucoadhesive intraurethral polymer suspension of alprostadil (ST-04) and will investigate the efficacy of 3 dose levels of ST-04 in adult males with a clinical diagnosis of Erectile Dysfunction (ED). Read more about this study
- Who is it for?
- Ages 21 to 75 years, men only
- Conditions the study is for
- Erectile Dysfunction (ED), Erectile Dysfunctions, Erectile Function
- What is being tested?
- ST-04
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 83 participants
- Where
- 1 siteCanada
- Study dates
- May 2026to May 2027
- Phase
- Phase 2
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 21 to 75 years
- Men only
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Have had a confirmed clinical diagnosis of ED for more than three months based upon IIEF
- Have failed PDE5 inhibitor therapy (inability to achieve an erection with adequate rigidity to allow penetrative sex)
- Ability to take oral medication (sildenafil) and be willing to adhere to the study intervention regimen
- Engaged in heterosexual relationship with partner for a minimum of 6 months
Who cannot join
- History of unstable medical or psychiatric condition that, in the opinion of the principal investigator, could impact the patient's ability to complete the study investigations or protocol.
- Spinal cord injury, or penile anatomical abnormalities
- Cardiovascular conditions that prevent sexual activity (NYHA Class II or higher, any angina, or uncontrolled CHF or severe coronary artery disease)
- History of myocardial infarction, stroke, or life-threatening arrhythmia within 6 months prior to enrollment into the study
- Use of anti-androgens, or oral or injectable androgens
- Documented hypotension or known orthostatic hypotension
Show all 10Show fewer
- Use of oral, topical or sublingual nitrates within 3 months prior to enrollment into the study
- Hepatic (Child-Pugh Class C) or renal failure (eGFR < 30)
- Inadequate response to intracavernosal injection therapy previously
- Peyronie's disease or Meatal stenosis
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site, 1 recruiting
- Recruiting
Vancouver Prostate Centre
Vancouver, British Columbia, V5Z1M9
Genevive - Clinical Trials Coordinator, 604-875-4111 ext. 67898, clinicaltrials@prostatecentre.com
Ryan Flannigan, MD
About this study
Official title: Phase 2 Clinical Trial of ST-04 Intraurethral Paste for Erectile Dysfunction
This is a single arm dose escalation trial of a mucoadhesive intraurethral polymer suspension of alprostadil (ST-04) and will investigate the efficacy of 3 dose levels of ST-04 in adult males with a clinical diagnosis of Erectile Dysfunction (ED). This study aims to determine if ST-04, with or without sildenafil, will improve erectile function (EF) compared to baseline.
Participants in this study will receive ST-04, a new formulation containing the vasodilator, alprostadil which is known to be an effective drug in treating erectile dysfunction. ST-04 will be dispersed along the urethra, forming a hydrogel which adheres to the lining of the urethra with the goal of penile tumescence and erection. Participants may receive up to 3 dose level escalations of ST-04 over a 12-week period, for a total of up to 11 administrations of ST-04. Dose escalation may also be done with and without sildenafil.
- Being tested
- ST-04
- Keywords
- Erectile Dysfunction, Erectile Function, Alprostadil, Sildenafil
- Medical subject headings
- Erectile Dysfunction
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ST-04Drug
ST-04 consists of an alprostadil polymer suspension designed for intraurethral application
| Study group | Role | What they receive |
|---|---|---|
| Single-Arm Dose Escalation | Experimental | Dose Level 1 is 500 μg of ST-04; Dose Level 2 is 1000 μg of ST-04 with or without Sildenafil; Dose Level 3 is 1500 μg of ST-04 with or without Sildenafil. Receives: Drug: ST-04 |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change from Baseline in the Erectile Function Domain of the IIEF Questionnaire
The IIEF is a validated questionnaire assessing erectile function, with total scores ranging from 5 to 25; higher scores indicate better erectile function
Measured: From baseline to 1 month after start of the last dose level (Week 4, 8, 12 respectively)
Secondary outcomes (4)
Change from Baseline in the Erectile Hardness Scale (EHS)
The EHS is a self-reported assessment of penile hardness on a scale of 0 (no engorgement) to 4 (complete rigidity).
Measured: From baseline to the end of treatment at week 4, 8 or 12 respectively
Change from Baseline in the Sexual Encounter Profile (SEP)
SEP is a log diary completed after each sexual attempt, providing information as to whether the erection was hard enough to penetrate (SEP 2), or whether it was maintained for completion (SEP 3).
Measured: From baseline to the end of treatment at week 4, 8 or 12 respectively
Percentage of Uses per Participant of ST-04 which Led to the Onset of Erection within up to 30 minutes of Application per Number of Intercourse Attempts
Percentage of participants using ST-04 that could achieve an erection and/or penetrative intercourse within 30 minutes of application per number of intercourse attempts.
Measured: From baseline to the end of treatment at week 4, 8 or 12 respectively
Incidence and Severity of Adverse events
Adverse events will be recorded at each follow-up visit and classified by type, severity, and relationship to the intervention.
Measured: From baseline to the end of treatment at week 4, 8 or 12 respectively
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 May 2026
- Study startMay 2026 (estimated)
- Primary completionApr 2027 (estimated)
- Study completionMay 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Erectile Dysfunction (ED)Studies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 2
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Single-Arm, Dose Escalation
- Masking
- None (open label)
- Enrolment
- 83 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Ryan Flannigan, MD
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor-investigator, Ryan Flannigan, MD, University of British Columbia
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07601646
- Sponsor's protocol ID
- H25-00542
- Status last verified
- May 2026
- First submitted
- 15 May 2026
- Last updated
- 22 May 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 22 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Phase 2 Clinical Trial of ST-04 Intraurethral Paste for Erectile Dysfunction
- ClinicalTrials.gov ID
- NCT07601646
- Acronym / sponsor ID
- H25-00542
- Keywords
- Erectile Dysfunction, Erectile Function, Alprostadil, Sildenafil
- Phase
- Phase 2
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 83 participants (estimated)
- Lead sponsor
- Ryan Flannigan, MDUniversity, hospital or other
- Study start
- May 2026 (estimated)
- Primary completion
- Apr 2027 (estimated)
- Study completion
- May 2027 (estimated)
- First posted
- 22 May 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This is a single arm dose escalation trial of a mucoadhesive intraurethral polymer suspension of alprostadil (ST-04) and will investigate the efficacy of 3 dose levels of ST-04 in adult males with a clinical diagnosis of Erectile Dysfunction (ED). This study aims to determine if ST-04, with or without sildenafil, will improve erectile function (EF) compared to baseline.
Participants in this study will receive ST-04, a new formulation containing the vasodilator, alprostadil which is known to be an effective drug in treating erectile dysfunction. ST-04 will be dispersed along the urethra, forming a hydrogel which adheres to the lining of the urethra with the goal of penile tumescence and erection. Participants may receive up to 3 dose level escalations of ST-04 over a 12-week period, for a total of up to 11 administrations of ST-04. Dose escalation may also be done with and without sildenafil.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Single-Arm, Dose Escalation
| Arm | Type | Receives |
|---|---|---|
| Single-Arm Dose Escalation | Experimental | Drug: ST-04Dose Level 1 is 500 μg of ST-04; Dose Level 2 is 1000 μg of ST-04 with or without Sildenafil; Dose Level 3 is 1500 μg of ST-04 with or without Sildenafil. |
Who may qualify
- Ages
- 21 to 75 years
- Sex
- Male only
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Have had a confirmed clinical diagnosis of ED for more than three months based upon IIEF
- Have failed PDE5 inhibitor therapy (inability to achieve an erection with adequate rigidity to allow penetrative sex)
- Ability to take oral medication (sildenafil) and be willing to adhere to the study intervention regimen
- Engaged in heterosexual relationship with partner for a minimum of 6 months
Key exclusion criteria (10 listed)
- History of unstable medical or psychiatric condition that, in the opinion of the principal investigator, could impact the patient's ability to complete the study investigations or protocol.
- Spinal cord injury, or penile anatomical abnormalities
- Cardiovascular conditions that prevent sexual activity (NYHA Class II or higher, any angina, or uncontrolled CHF or severe coronary artery disease)
- History of myocardial infarction, stroke, or life-threatening arrhythmia within 6 months prior to enrollment into the study
- Use of anti-androgens, or oral or injectable androgens
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| ST-04ST-04 consists of an alprostadil polymer suspension designed for intraurethral application | Drug | Single-Arm Dose Escalation |
Primary outcome
Change from Baseline in the Erectile Function Domain of the IIEF Questionnaire
Time frame: From baseline to 1 month after start of the last dose level (Week 4, 8, 12 respectively)
The IIEF is a validated questionnaire assessing erectile function, with total scores ranging from 5 to 25; higher scores indicate better erectile function
4 secondary outcomes
Change from Baseline in the Erectile Hardness Scale (EHS)
Time frame: From baseline to the end of treatment at week 4, 8 or 12 respectively
Change from Baseline in the Sexual Encounter Profile (SEP)
Time frame: From baseline to the end of treatment at week 4, 8 or 12 respectively
Percentage of Uses per Participant of ST-04 which Led to the Onset of Erection within up to 30 minutes of Application per Number of Intercourse Attempts
Time frame: From baseline to the end of treatment at week 4, 8 or 12 respectively
Incidence and Severity of Adverse events
Time frame: From baseline to the end of treatment at week 4, 8 or 12 respectively
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 May 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 2 study testing ST-04 in people with Erectile Dysfunction (ED) and Erectile Dysfunctions, run by Ryan Flannigan, MD at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 22 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Each site lists its own contact: choose the nearest one under Trial locations. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change from Baseline in the Erectile Function Domain of the IIEF Questionnaire (time frame: From baseline to 1 month after start of the last dose level (Week 4, 8, 12 respectively)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 22 May 2026; AzTrials last refreshed its copy on 7 Nov 2026.